A high-sensitivity strain sensor based on the core-offset fiber with a micro air bubble

Abstract

A highly sensitive optic-fiber strain sensor based on the air-microbubble Fabry–Perot interferometer (FPI) formed in a core-offset tapered fiber is proposed. By drawing tapers on the staggered spliced single-mode fibers, micro air bubbles with an average wall thickness of 2.6 μm are formed. The experimental results show that the sensor has a high strain sensitivity of 17.24 pm/με and good linear response in the range of 0–1500 με. A numerical simulation model is developed to study the axial strain response, and the results show that the core-offset structure increases the strain sensitivity by 46 %. In addition, the sensor has a temperature sensitivity of 3.43 pm/°C and a cross-sensitivity with strain as low as 0.199 με/°C over the range of 50–350 °C.